21135912243 has 16 divisors (see below), whose sum is σ = 28245230496. Its totient is φ = 14058636800.

The previous prime is 21135912221. The next prime is 21135912253. The reversal of 21135912243 is 34221953112.

It is a cyclic number.

It is not a de Polignac number, because 21135912243 - 2¹⁰ = 21135911219 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21135912253) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3150793 + ... + 3157493.

It is an arithmetic number, because the mean of its divisors is an integer number (1765326906).

Almost surely, 2^21135912243 is an apocalyptic number.

21135912243 is a deficient number, since it is larger than the sum of its proper divisors (7109318253).

21135912243 is a wasteful number, since it uses less digits than its factorization.

21135912243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8934.

The product of its digits is 12960, while the sum is 33.

The spelling of 21135912243 in words is "twenty-one billion, one hundred thirty-five million, nine hundred twelve thousand, two hundred forty-three".